Jaw construction for lift trucks



J. G. LORD JAW CONSTRUCTION FOR LIFT TRUCKS Feb. 19, 1957 4 Sheets-Sheet 1 Filed July 8, 1955 FIG. 8

INVENTOR JOHN G. LORD BY HIS ATTORNEY Feb. 19, 1957 J. G. LORD 2,782,066

JAW CONSTRUCTION FOR LIFT TRUCKS Filed July 8, 1955 4 Sheets-Sheet 2 |l2 C llOa FIG. 5

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FIG. 2

INVENTOR.

JOHN LORD Feb. 19, 1957 J. G. LORD JAW CONSTRUCTION FOR LIFT TRUCKS 4 Sheets-Sheet 3 Filed July 8, 1955 1"! III INVENTOR. JOHN G. LORD FIG.

Feb. 19, 1957 J. G. LORD JAW CONSTRUCTION FOR LIFT TRUCKS 4 Sheets-Sheet 4 Filed July 8, 1955 V IIOd LJW a I I I I I I I 6 I I I I I I I I FIG.7

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INVENTOR. JOHN G. Lo B FIG. 6

United States Patent JAW CONSTRUCTION FOR LIFT TRUCKS John G. Lord, Swarthmore, Pa., assignor, by mesne assignments,to Shell Development -Co., a corporation Application July 8, 195'5,Serial No. 520,761

3 Claims. (Cl. 294-9 9) This invention relates .to improvements-in load-handling mechanisms, and more particularly to an improved material-handling and load-gripping jaw for lift trucks and the like.

In lift trucks and other lift mechanisms having laterally movable jaws, the satisfactory gripping of load units whose dimensions are not quite uniform in a fore-andaft direction or in an up-and-down direction has long presented a problem.

This invention has an objectthe provision of :a loadhandling mechanism having laterally moving jaws, which jaws are able to accommodate load units having somewhat irregular shapes.

A further object of the present invention is the provision of an improved lift truck.

Other .objects will appear hereinafter.

For the purpose of illustrating the invention, there is shown inthe accompanying drawings one form thereof which is at present-preferred, although it is to be understood that the various instrumentalities of which the invention consists can be variously arranged and organized and that theinvention is not limited to the precise arrangements and organizations .of the instrumentalities as herein shown and described.

In the following drawings, like reference characters refer to like parts.

Figure '1 is a perspective view of a portion of a lift truck including one form of load-handling device of the present invention.

Figure 2 is .a vertical sectional view taken on line 2-2 of Figure 1.

Figure 3 is a horizontal sectional view of one of .the load-grasping jaws through the lowermost prong thereof.

Figure '4 is an enlarged view of the circled area designated 4--4 of Figure 3.

Figure 5 is a vertical sectional view on line 5-5 of Figure 1.

Figure 6, is a horizontal sectional view of one of the load-grasping jaws through the center prong thereof.

Figure 7 is an enlarged view of the circled area designated 7-7 of Figure 6.

Figure 8 is a side view showing the back of one of the load-grasping jaws.

Referring to the drawings, a portion of an industrial lift truck of type well-known in the art is indicated generally by reference .numeral 20. This ,lift truck is provided with .a pair of front wheels 22 and a pair of rear wheels 24.

A load-lifting carriage designated generally as 46 is secured to the front of lift truck.

Load-lifting carriage 46 comprises a pair of jaws designated 48 and 50, and individual jaw-actuating means designated '52 and 54 for actuating respective jaws 48 and 50.

The jaw-actuating means 52 and 54 form no part of the present invention, and other jaw-actuating means than those here shown may be substituted therefor. However, jaw-actuating means 52 and 54 are to be preferred.

Jaw-actuating means .52 comprises a guide or way 56 having .;guidetracks 58 and 60. A primary slider designated 62 is .guided by guide tracks 58 and 60.

A cylinder 64 is fixedly joined by means of anchor plate 66 to the floor of guide or Way 56. Piston 'rod 68 is connected to a thrust plate portion 70 of primary slider 62. Primary slider 62 does not contact cylinder 64 and its movement within guide or way 56 is not obstructed thereby.

A secondary slider 72 rides in a guide .or way formed in primary slider 62. Secondary .slider 72 is joined to primaryslider62 *by means of chain-and-sprocket means 74, with one link on the front span of the chain in the chain-and-sprocket74 being vfixedly secured to the secondary slider 72 and a diametrically opposite link on the rear span of the chain in the chain-and-sprocket means 74 being fixedly secured to guide track 60. This permits a multiplication of the relative rate of movement of the secondary slider 72in respect to the rate of movement of primary slider 62, to be achieved. Thus, an incremental movement of primary slider 62 in either direction will bedoubled by secondary slider 72in the same direction.

The movement of piston rod 68 either inwardly or outwardly causes rprimary slider 62 and secondary slider 72 to move in the same direction, the latter moving, as here tofore noted, at double the rate of the former. In this manner jaw 48 may be moved independently of jaw 50.

Jaw-actuating means 54 is similar to jaw-actuating means 52, and includes a guide or way 78 formed between guide tracks 60 and 80. A primary slider -82, having a thrust plate portion 84 is disposed within'and guided by guide 78in the same manner as primary slider 62 is disposed within and guided by guide 56. Similarly, a cylinder 86 having an anchor plate 88 is joined to guide 78 in the same fashion as cylinder '64 is joined to guide 56. Piston rod 90 extends from cylinder 86'to thrust plate portion 84 of primary slider 82.

A secondary slider 92 and a chain-and-sprocket means 94 constructed and arranged in identical fashion as secondary slider 72 and chain-and-sprocket means 74 are also provided.

laws 48 and 50 are secured to respective secondary sliders 72 and 92 in identical fashion. Thus, secondary sliders 72 and 92 are provided with respective L-shap'ed flanges 96 and 98, respectively, which have the base of the .L directed outwardly and frontwardly disposed and the top of the L integral with the front surface of the secondary sliders. Flanges 96 and 98 are identical in height, extending generally from a point on the planeof the uppermost surface of primary slider 62 to a point on the plane of the lowermost surface of primary slider 82.

As seen most clearly-in Figures 3 and 6, each of the L-shaped flanges (L-shaped flange 98 being shown in these figures) cooperates with the vplanar front surface of each of the secondary sliders 72 and 92 to effect rabbeted engagement with the back plate of the jaws. Thus, backplate 102 of jaw 50 is rabbeted with flange 96, and back plate 100 of jaw 48 is rabbeted with flange 98. Threaded bolts 76 serve to permanently anchor hack plates 100 and 102 to secondary sliders 72 and 92.

Each of jaws 48 and 5 0 comprises a pair of cushion pads or members; jaw 48 comprising cushion pads or members. 104 and 106, and jaw 50 comprising cushion pads or members 108 and .110.

Each of cushion pads 104, 106, 108 and 110 comprises an outer metal plate and an inner plastic liner or surfacing. Thus, in thecase of cushion pad 110, the outer metal plate is designated 110a, and the inner plastic liner or surface is designated 1310b. The plastic .liner 110b, may be formed of any of the well-known plastics which possess resilient and. durable properties.

The mounting of the cushion pads 104, 106, 108 and 110 on jaws 48 and 50, achieves a high degree of flexibility. This is accomplished by having each of the cushion pads floatingly mounted on a unit of three jaw prongs. To illustrate this method of mounting, the mounting of cushion pad 110 on its jaw prongs will be described. However, each of the other cushion pads 104, 106 and 108 are similarly mounted on their jaw prongs.

Cushion pad 110 is mounted on jaw prongs 112, 114 and 116 which extend forwardly at right angles from back plate 102 of jaw 48. Prongs 112, 114 and 116 are integral with back plate 102. Jaw prongs 112 and 116 are substantial mirror images of each other and comprise relatively thick prong members which extend forwardly almost to the end of cushion pad 110. Jaw prongs 112 and 116 are of substantially uniform crosssectional thickness for about two-thirds of their entire length. The frontmost third of jaw prongs 112 and 116 tapers inwardly on its outer surface to provide a relatively thin front portion. Jaw prongs 112 and 116 are not fixedly attached or otherwise permanently secured to the back of metal plate or layer 110a of cushion pad 110; thus, the front tip 118 of jaw prong 116 is notched at 120 and is housed within a metal strap 122, which is welded onto the'back of metal plate 110a of cushion pad 110 (Figures 3 and 4). Strap 122 serves to prevent up-and-down dislodgement of jaw prong 116. Jaw prong 112 is, as heretofore indicated, identical with, or a mirror image of, jaw prong 116 and lies closely adjacent metal layer 110:: with its tip 124 disposed within strap 126, which is welded to the back of metal plate 110a.

Center jaw prong 114 is appreciably thinner than jaw prongs 112 and 116, and extends forwardly for but about a half or less than one half the length of jaw prongs 112 and 116. Jaw prong 114 is not fixedly secured to the back of plate 110a but its tip portion 128 is retained in a strap 130 which is welded to the back surface of plate 110a. Tip 128 is provided with a circular aperture 132 in its central portion.

A bolt or pin 134 having a relatively wide threaded upper portion 135 and a relatively thin smooth-surfaced lower portion 136 is retained in threaded engagement within a threaded opening in strap 130, with the lower portion 136 nested within aperture 132. As aperture 132 is of somewhat larger diameter than the diameter cushion pad flexibility both vertically and in a fore-andaft direction may be achieved.

Several longitudinal webs on the back of each of the cushion pads 104, 106, 108 and 110 are provided to strengthen the cushion pads. These are indicated in relation to pad 110 as 1100. As will be seen, for example in Figures 2 and 8, the straps encasing the tips of the prongs bridge adjacent Webs to form sockets for the prong tips. Vertical webs are also provided on the back of each cushion pad to further strengthen the cushion pads. These are indicated in relation to pad 110 as 110d.

Thus, if a load is gripped mainly in the center portion of the cushion pads, the center prong of each jaw prong unit will be pushed outwardly slightly causing the cushion pads to flex, with the end portions of the jaw disposed relatively inwardly, giving optimum gripping action. A similar flexing action is obtained where the maximum gripping pressure is exerted against the ends of the cushion-pads. Thus, pressure on the frontmost end of the cushion members will cause the cushion members to fulcrum on the center prong.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

Having described the invention, the following is claimed:

1. A grip jaw for lift trucks and the like including a cushion pad, socketed retention members fixedly secured at spaced vertical distances from each other to the back of said cushion pad, a unit of three support prongs juxtaposed to the rear surface of said cushion pad, the rear end portion of each of said prongs joined together, the center support prong extending forwardly a lesser distance than the outer prongs, said socketed retention members positioned on the back of said cushion pad arranged to receive the tips of said support prongs, the tips of said support prongs disposed within the sockets of said retention members, but not fixedly joined thereto, whereby said cushion padmay be moved in respect to said support prongs, and means for preventing the disengagement of said cushion pad from said support prongs comprising a projection fixedly secured to the center recessed member with the free end portion of said projection disposed within an aperture in the front tip portion of said center prong.

2. A grip jaw for lift trucks and the like including a cushion pad, a unit of three support prongs juxtaposed to the rear surface of said cushion pad, socketed retention members secured at spaced vertical distances to the rear of said cushion pad, a back plate joined to said support prongs at the rear thereof, the outer two jaw prongs being relatively long and having their front-most tip portions disposed within the sockets of said retention members, the sockets within said retention members being substantially larger than the front-most tip portions of said outer prongs thereby permitting said outer prongs to move therewithin, the center-most prong of said support unit being bothrelatively short and relatively thin in cross-section compared with said outer prongs, the front tip portion of said center prong disposed within the socket of a retention member, an aperture in the front tip portion of said center prong, and a pin fixedly joined to the last mentioned retention memher having one end disposed within the aperture in said center prong.

3. A grip jaw for lift trucks and the like including a cushion pad, three socketed retention members secured at spaced vertical distances from each other to the rear surface of said cushion pad, three support prongs juxtaposed to the rear surface of said cushion pad, the rear end portion of said prongs joined together, the center support prong extending forwardly a lesser distance than the outer prongs and having a higher degree of flexibility than the outer prongs, said socketed retention members disposed on the rear surface of said cushion pad and arranged to receive the tips of said support prongs, and means for preventing the disengagement of said cushion pad from saidsupport prongs comprising a projection fixedly secured to the center socketed retention member having a free end portion detachably disposed within an aperture in the front tip portion of said center support prong, whereby said cushion pad may be moved in respect to said support prongs and may fiexingly accommodate irregularly-shaped load-units.

References Cited in the file'of this patent UNITED STATES PATENTS 166,599 Frederick Aug. 10, 1875 590,747 Tidler Sept. 28, 1897 2,681,162 Ehmann 111118 15, 1954 2,704,167 Framhein Mar. 15, 1955 

